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(Solved): Suppose that there are only two types of stars in the Universe: low mass stars with masses of M_(low ...
Suppose that there are only two types of stars in the Universe: low mass stars with masses of M_(low )=1M_(o.) and high mass stars with masses of M_(hi)=100M_(o). When stars form, 1000 low mass
stars are formed for every high mass star formed. Assume the low mass stars have main sequence lifetimes of 9 Gyr and the high mass stars have main sequence lifetimes of 10 Myr .
Suppose that stars form in a galaxy at a constant rate of 10M_(o.) per year for 11 Gyr .
Now assume the low mass stars have a luminosity of 1L_(o.) for 8 Gyr while they are on the main sequence and then a luminosity of 10^(3)L_(o.) for 1 Gyr when they are on the red giant branch. Their luminosity after 9 Gyr is negligible and can be ignored. High mass stars have
a luminosity of 10^(6)L_(o.) when they are on the main sequence and then explode as supernovae.
Assuming the star formation history from above, what is the ratio of luminosity coming from high and low mass stars today?
(where M_(o )=solar mass and L_(o )= solar luminosity)